Table: Summarized Geochemical Result of Analytical
Samples of Heavy Element Concentration in River Iyiokwu in Abakaliki and its Environs
in mg/kg
S/N
|
Sample No
|
Longitude
|
Latitude
|
Pb
|
Zn
|
Cu
|
As
|
Cd
|
Ni
|
|
1
|
UNA/1
|
8005′ 04. 84″E
|
6017 48.72″E
|
4.2
|
24.3
|
1.6
|
0
|
0
|
0
|
|
2
|
UNA/2
|
8005′ 12.76″E
|
6017 52.98″E
|
1.4
|
26.5
|
1.9
|
4.5
|
0
|
0.1
|
|
3
|
UNA/3
|
8005′ 24.80″E
|
6017 32.48″E
|
1.7
|
11.9
|
3.2
|
0.1
|
1.1
|
0
|
|
4
|
UNA/4
|
8005′ 36.58″E
|
6018 24.46″E
|
1.2
|
37.3
|
10.2
|
0.8
|
0.8
|
0.6
|
|
5
|
UNA/5
|
8005′ 48.25″E
|
6018 28.28″E
|
0.5
|
40.9
|
0.9
|
0
|
2.6
|
0.4
|
|
6
|
UNA/6
|
8006′ 01.21″E
|
6018 32.98″E
|
0.3
|
30.0
|
10.1
|
40
|
1.8
|
1.2
|
|
7
|
UNA/7
|
8006′ 12.82″E
|
6018 31.70″E
|
1.1
|
21.4
|
1.9
|
0
|
1.2
|
0
|
|
8
|
UNA/8
|
8006′ 24.16″E
|
6018 31.52″E
|
0.7
|
23.3
|
1.6
|
0
|
0
|
3.8
|
|
9
|
UNA/9
|
8006′ 34.40″E
|
6018 53.85″E
|
0
|
43.1
|
15.8
|
0.3
|
5.5
|
1.2
|
|
10
|
UNA/10
|
8006′ 48.72″E
|
6018 31.72″E
|
1.5
|
24.4
|
12.8
|
0.5
|
1.3
|
0.9
|
|
11
|
UNA/11
|
8007′ 00.88″E
|
6018 39.77″E
|
1.2
|
37.3
|
17.7
|
0.7
|
12.2
|
12.4
|
|
12
|
UNA/12
|
8007′ 12.79″E
|
6018 54.92″E
|
5.6
|
21.4
|
0.4
|
0.9
|
0
|
0
|
|
13
|
UNA/13
|
8007′ 24.92″E
|
6018 60.32″E
|
6.7
|
10.7
|
0
|
0
|
0.5
|
0
|
|
14
|
UNA/14
|
8007′ 36.40″E
|
6018 36.72″E
|
6.6
|
21.1
|
0
|
0
|
0
|
0
|
|
15
|
UNA/15
|
8007′ 48.98″E
|
6018 61.32″E
|
7.4
|
25.4
|
2.4
|
0.4
|
3.5
|
0.8
|
|
16
|
UNA/16
|
8008′ 02.32″E
|
6018 62.86″E
|
9.1
|
34.7
|
0.9
|
0.7
|
5.4
|
0.7
|
|
17
|
UNA/17
|
8008′ 12.84″E
|
6018 52.28″E
|
7.5
|
30.8
|
10.7
|
0.7
|
1.1
|
0.6
|
|
18
|
UNA/18
|
8008′ 24.80″E
|
6018 58.84″E
|
6.3
|
40.1
|
10.6
|
1.1
|
0
|
0.5
|
|
19
|
UNA/19
|
8008′ 36.58″E
|
6017 46.72″E
|
7.1
|
29.8
|
10.4
|
1.0
|
0.4
|
0.8
|
|
20
|
UNA/20
|
8008′ 46.82″E
|
6017 52.38″E
|
9.1
|
30.0
|
9.7
|
0
|
6.8
|
1.6
|
Table 4: Statistical
analysis of various concentration of element in stream sediment in mg/kg
|
Statistics element
|
Mean
Mg/kg
|
Variance
|
Standard deviation
|
Mode min conc.
|
Max conc.
|
Range
|
Mode
|
|
Pb
|
4.17
|
10.34
|
3.22
|
0.3
|
9.1
|
8.8
|
9.1
|
|
Zn
|
28.22
|
80.41
|
8.9
|
10.7
|
40.9
|
30.2
|
30.0
|
|
Cu
|
6.82
|
32.60
|
5.71
|
0.4
|
17.7
|
17.3
|
1.6
|
|
Cd
|
3.98
|
11.79
|
3.43
|
0.4
|
12.2
|
11.8
|
1.1
|
|
As
|
3.16
|
119.08
|
10.91
|
0.1
|
40
|
39.9
|
0.7
|
|
Ni
|
1.83
|
10.15
|
3.19
|
0.1
|
12.4
|
12.3
|
1.2
|
Table 5: Average abundance
of the analysed heavy metals in the Earth’s Crust and Shale after Levinson (1971).
|
Element
|
Earth’s crust
|
Shale
|
|
Lead (Pb)
|
12.5
|
20
|
|
Zinc (Zn)
|
70
|
90
|
|
Copper (Cu)
|
55
|
50
|
|
Arsenic (As)
|
1.8
|
10
|
|
Cadmium (Cd)
|
0.15
|
0.3
|
|
Nickel (Ni)
|
75
|
80
|
4.2.1 Lead (Pb)
Around River Iyiokwu in Abakaliki and its environs, lead was evenly
distributed in the stream sediments as shown in Table 3 with only 1 location
showing deficiency (location 9). The mean concentration of each (Pb) is
4.17mg/kg (table 4), while the maximum concentration was 9.10mg/kg, with a
minimum concentration of 0.3mg/kg. Its range was at 8.8mg/kg. From the analysis
of the sample collected from the stream sediments, it shows that lead is below
its toxic level. Magma fluid is the regular geological source of Pb which gives
rise to Pb –Zn deposits in ore-bodies. Its low toxicity in the stream sediments
may by contributed to the long distance of transportation and deposition.
Sample locations
4.2.2 Zinc (Zn)
In the study area, the
maximum concentration of zinc was 40.9mg/kg and its minimum concentration at
10.7mg/kg (table 4). Zinc was evenly distributed in the stream sediments due to
its existence with mobile element in the study area. It also has a mean
concentration of 28.22mg/kg and a range of 30.2mg/kg. The evenly distribution
of Zn shows high concentration in the derelict mines of Abakaliki (ministry of
works quarry) and low in stream sediments far from the mine.
Sample locations
4.2.3 Copper (Cu)
Copper was noticed to be
below its tolerable level in normal soil which is 30mg/kg. Copper was almost
evenly distributed in the stream sediments of river Iyiokwu with 2 sample
locations showing deficiency in copper (locations 13 & 14).
Its mean concentration is 6.82mg/kg.
The maximum concentration of Cu was 17.7mg/kg (L11) and its minimum concentration
was 0.4 mg/kg (L12). Copper being far below its tolerable level in normal soil
may be as a result of its distance from the primary source of the deposit that
contains copper.
Sample locations
4.2.4 Cadmium
Cadmium was not evenly distributed
in the whole twenty sample locations collected for the analysis. Five (5)
sample locations shows deficiency in cadmium after the analysis. Thus its total
mean concentration is 3.98mg/kg. It has a maximum concentration of 12.2mg/kg (location
11) and a minimum concentration of 0.4mg/kg (L19). The concentration of cadmium
in the stream sediments of River Iyiokwu is attributed to human activities and
weathering of parent materials rich in cadmium such as black shale.
Sample locations
4.2.5 Arsenic (As)
Arsenic was not evenly dispersed in the stream sediments of river
Iyiokwu in Abakaliki and its environs. Seven sample locations shows deficiency
in Arsenic as regards to the analysis. Most of the concentration of As in most
of the samples is below the detection limit of the analytical equipment. Its
total mean concentration is 3.16mg/kg. It has a maximum concentration of
40mg/kgs (Location 6). Minimum concentration of 0.1mg/kgs (location 3). Its
deficiency may be as a result of its distance from the source.
Sample locations
Fig 11: Bar chart showing
the distribution of arsenic in the different sample locations
4.2.6 Nickel (Ni)
There was deficiency of nickel in 6 Locations (Locations 1, 3, 7,
12, 13, 14). Thus, It was not evenly dispersed. It has total mean concentration
of 1.83mg/kg, its maximum concentration is 12.4mg/kg (Location 11) and a
minimum concentration of 0.1mg/kg (Location 2).
4.3 POLLUTION STATUS OF THE
STREAM SEDIMENTS
In characterizing the contamination
level in stream sediments in Iyiokwu
River, the approach
described in the United States Environmental Protection Agency (USEPA), Mid-Atlantic
Intergrated Assessment (MAIA) for estuaries
1997-1998 Summary Report and the United States Geological Survey Water
Resources Investigation Report 95-4267 was espoused. This was in line with the
sediment quality guideline established by Long. et al. (1995). After reviewing
nine elements that have ecological and biological effects on organisms, Effect
Range Low (ERL) was defined as the lowest concentration of metals that produced
adverse effects in 10% of organisms reviewed in the MAIA project. The Effect
Range Median (ERM) designates the level at which 50% of the organisms studied reported
harmful effects. Metals concentration in the sediments above ERM are likely to
be very toxic. Table 6 below shows the ERL and ERM limits for metal
contaminants in sediments.
Table 6: ERL and ERM
limits for metals (USEPA-MAIA 1998)
|
Metals
|
ERL values
|
ERM values
|
|
Lead (Pb)
|
47
|
220
|
|
Zinc (Zn)
|
150
|
410
|
|
Copper (Cu)
|
34
|
270
|
|
Arsenic (As)
|
1.2
|
9.6
|
|
Cadmium (Cd)
|
8.2
|
70
|
|
Nickel (Ni)
|
21
|
52
|
From table 6 above,
the ERM for lead is 220mg, its total concentration in all sampled locations is
below the ERM and ERL which is 47mg. Hence, lead concentration is below the
toxic level. The ERM for zinc is 410, the highest concentration of zinc is 43.1mg/kg
thus, its way below the toxic level. Also, ERM for copper is 270 and the
highest concentration is 17.7 (Location 11) thus explains that the
concentration of copper is below the toxic level.
Again, the ERM for arsenic, cadmium and nickel being 9.6,
70 and 52 respectively shows that they are way below the toxic level.
4.4 Geoaccumulation Index
(Igeo)
This is defined by
the formular Igeo= log2 Cn/1.5Bn, where Cn is the measured concentration
of metals in pelitic sediment fraction and Bn is the geochemical background
value (Average Shale) in the earth’s crust (see table 5). The constant 1.5
allows for natural fluctuations in the content of a given substance in the
environment and very small anthropogenic influences. Table 7 below shows the
classes of geoacumulation index.
Table 7: Classes Of The
Geoacumulation Index.
|
Class
|
Value
|
Soil/sediment quality
|
|
0
|
Igeo<0
|
Practically uncontaminated
|
|
1
|
0<Igeo<1
|
Uncontaminated to moderately contaminated
|
|
2
|
1<Igeo<2
|
Moderately uncontaminated
|
|
3
|
2<Igeo<3
|
Moderately contaminated-heavily contaminated
|
|
4
|
3<Igeo<4
|
Heavily contaminated
|
|
5
|
4<Igeo<5
|
Heavily contaminated-extremely contaminated
|
|
6
|
5<Igeo<6
|
Extremely contaminated
|
Table 8: Showing the Geoacumulation
Index of the Analysed Elements
|
s/n
|
Pb
|
Zn
|
Cu
|
As
|
Cd
|
Ni
|
|
1
|
0.042
|
0.054
|
0.006
|
0
|
0
|
0
|
|
2
|
0.014
|
0.059
|
0.007
|
0.090
|
0
|
0.0003
|
|
3
|
0.017
|
0.027
|
0.013
|
0.002
|
0.736
|
0
|
|
4
|
0.012
|
0.083
|
0.041
|
0.016
|
0.535
|
0.002
|
|
5
|
0.005
|
0.091
|
0.004
|
0
|
1.739
|
0.001
|
|
6
|
0.003
|
0.067
|
0.041
|
0.803
|
1.204
|
0.003
|
|
7
|
0.011
|
0.048
|
0.007
|
0
|
0.803
|
0
|
|
8
|
0.007
|
0.052
|
0.006
|
0
|
0
|
0.010
|
|
9
|
0
|
0.096
|
0.063
|
0.006
|
3.679
|
0.003
|
|
10
|
0.015
|
0.054
|
0.0514
|
0.010
|
0.870
|
0.002
|
|
11
|
0.012
|
0.083
|
0.071
|
0.014
|
8.160
|
0.031
|
|
12
|
0.056
|
0.048
|
0.002
|
0.018
|
0
|
0
|
|
13
|
0.067
|
0.024
|
0
|
0
|
0.344
|
0
|
|
14
|
0.066
|
0.047
|
0
|
0
|
0
|
0
|
|
15
|
0.074
|
0.057
|
0.009
|
0.008
|
2.341
|
0.002
|
|
16
|
0.091
|
0.077
|
0.004
|
0.014
|
3.612
|
0.0018
|
|
17
|
0.075
|
0.069
|
0.043
|
0.014
|
0.736
|
0.002
|
|
18
|
0.063
|
0.089
|
0.043
|
0.022
|
0
|
0.001
|
|
19
|
0.071
|
0.066
|
0.042
|
0.020
|
0.268
|
0.002
|
|
20
|
0.091
|
0.067
|
0.039
|
0
|
4.348
|
0.004
|
Following the geoacumulation
index from Table 8 above, it is deduced that five (5) of the heavy metals satisfy
class 0 (practically uncontaminated) of Table 7 above (Classes of geoacumulation
index) except cadmium. Cadmium was found to show extreme contamination with the
highest value occurring at Sample Location 11 (Afikpo rd) at 8.160mg/kg. They
all fall between Abakaliki metropolis due to pollution of drainage system and
activities of the people within the metropolis.
4.5 Pearson Correlation
Table 9: Pearson
Correlation Coefficient Of Analysed Elements
|
|
Pb
|
Zn
|
Cu
|
As
|
Cd
|
Ni
|
|
Ni
|
-0.238
|
0.287
|
0.513
|
-0.011
|
0.760
|
1
|
|
Cd
|
-0.006
|
0.444
|
0.516
|
0.046
|
1
|
|
|
As
|
-0.273
|
0.061
|
0.163
|
1
|
|
|
|
Cu
|
-0.207
|
0.577
|
1
|
|
|
|
|
Zn
|
-0.139
|
1
|
|
|
|
|
|
Pb
|
1
|
|
|
|
|
|
From table 9 above, there is a fairly strong positive correlation
between copper and zinc, copper and cadmium, copper and nickel. Whereas cadmium
and zinc are weakly correlated. Cadmium and nickel showed the highest positive
correlation with a value of 0.760
4.6 POLLUTION INDEX
The pollution index
is given by the formular = concentration in metal (mg/kg) divided by the ERM ( Effect
Range Median). Table 10 below shows the pollution index for the analysed
samples. Comparing the pollution index data and the analysed result data, it
shows that all the samples has low or no level of toxicity.
Table 10: Pollution Index
of the Analysed Elements
|
s/n
|
Pb
|
Zn
|
Cu
|
As
|
Cd
|
Ni
|
|
1
|
0.019
|
0.059
|
0.006
|
0
|
0
|
0
|
|
2
|
0.006
|
0.065
|
0.007
|
0.469
|
0
|
0.002
|
|
3
|
0.008
|
0.029
|
0.012
|
0.010
|
0.016
|
0
|
|
4
|
0.005
|
0.091
|
0.038
|
0.083
|
0.011
|
0.012
|
|
5
|
0.002
|
0.096
|
0.003
|
0
|
0.037
|
0.008
|
|
6
|
0.001
|
0.073
|
0.037
|
4.167
|
0.026
|
0.023
|
|
7
|
0.005
|
0.052
|
0.007
|
0
|
0.017
|
0
|
|
8
|
0.003
|
0.056
|
0.006
|
0
|
0
|
0.073
|
|
9
|
0
|
0.105
|
0.059
|
0.323
|
0.079
|
0.023
|
|
10
|
0.007
|
0.060
|
0.047
|
0.052
|
0.019
|
0.017
|
|
11
|
0.005
|
0.091
|
0.066
|
0.073
|
0.174
|
0.238
|
|
12
|
0.025
|
0.052
|
0.001
|
0.094
|
0
|
0
|
|
13
|
0.030
|
0.026
|
0
|
0
|
0.007
|
0
|
|
14
|
0.030
|
0.052
|
0
|
0
|
0
|
0
|
|
15
|
0.034
|
0.062
|
0.008
|
0.042
|
0.050
|
0.015
|
|
16
|
0.041
|
0.085
|
0.003
|
0.073
|
0.0077
|
0.013
|
|
17
|
0.034
|
0.075
|
0.040
|
0.073
|
0.016
|
0.012
|
|
18
|
0.029
|
0.097
|
0.039
|
0.115
|
0
|
0.009
|
|
19
|
0.032
|
0.073
|
0.039
|
0.104
|
0.006
|
0.015
|
|
20
|
0.041
|
0.073
|
0.036
|
0
|
0.097
|
0.031
|